It has become more and more necessary for medical/dental instruments, such as pliers, to be disinfected and sterilized. Present methods employed for such disinfection or sterilization often cause discoloration or corrosion of the orthodontic instruments, even those made of stainless steel. Compared to stainless steel, titanium based alloys can typically last much longer in the harsh environments found in such disinfection and sterilization methods. In addition, titanium based alloys are generally lighter in weight than stainless steel. Thus, orthodontic pliers made from titanium based alloys are more corrosion resistant and generally lighter in weight than comparable pliers made of stainless steel. The improved corrosion resistance can increase the useful life of the pliers, and the lighter weight can provide better response (i.e., feel) when the pliers are manipulated, such as when used for bending wires.
Heretofore, however, titanium based alloys have been considered unsuitable for making medical/dental pliers. Medical/dental pliers, like most pliers, generally include a pair of plier halves, with each plier half having a handle, a pivot section, and a jaw with a gripping face. The two plier halves are pivotally connected at their pivot sections such that relative movement of the handles will cause the gripping surfaces to come together in a gripping fashion. One problem with pliers made from titanium based alloys is that they are likely to exhibit excessive wear, such as galling, at the pivot joint. In addition, the gripping faces of the jaws of such pliers are susceptible to being deformed or having indentations formed therein when an object harder than the titanium based alloy material, for example a stainless steel orthodontic appliance, is gripped between the jaws.
It is known to coat the gripping faces of medical/dental pliers made from titanium based alloys with a layer of titanium nitride to provide a wear resistant gripping surface on the gripping faces. However, the gripping faces of these pliers are still susceptible to being indented when used to hold hard objects. In addition, when such an indentation occurs, the titanium nitride coating is prone to crack.